Temperature responsive nano-phase separated waterborne polymer dispersions

Résumé

In this PhD thesis a strategy was developed to synthesize by means of RAFT in safe and environmentally friendly way temperature responsive waterborne dispersions of well-defined block copolymers which form nanophase separated particles containing crystalline/soft and hard/soft domains. Next to the synthesis, the film formation behavior of the block copolymer dispersions was studied in order to understand how temperature responsiveness can be applied to control morphology and the resulting material properties of the films.Block copolymers with hard/soft domains and crystalline/soft domains were synthesized to explore the use of the Tg of the amorphous hard phase or the melting temperature of the crystalline phase as triggering temperature. To achieve stable waterborne dispersions of well-defined block copolymers, the synthesis was done in two reactions steps and carefully studied to find the conditions of controlled polymerization. First, miniemulsion polymerization was used for the synthesis of the crystalline or hard domains. Then, in the second step, the controlled polymerization was continued with 2-ethyl hexyl acrylate to form soft domains. The effect of the polymer architecture (diblock, triblock, different Mw of the blocks) on particle morphology and that of the particle morphology on film morphology and mechanical properties of the films were investigated. As the final step, the block copolymers were tested as heat seal lacquers to explore this as a potential application field for the temperature responsiveness.